This invention relates to a process for making an abrasive sintered product and more particularly, to a process for extracting a useful abrasive product from a sintered unitary structure having at least one first region containing a plurality of abrasive particles embedded therein and at least one second region containing substantially less or no abrasive particles adjacent the first region. The abrasive product can then be readily extracted from the structure by cutting or otherwise fracturing the structure through the second region or along the borderlines between the two regions.
U.S. Pat. Nos. 4,925,457; 5,092,910; and 5,791,330 teach cutting abrasive products out of structure of a sintered retaining matrix containing a plurality of abrasive particles. The structure can contain a mesh-type material as shown in the ""457 and ""910 patents or no mesh-type material as shown in the ""330 patent. However, in these structures the particles are distributed throughout the structure so that if a product is to be cut out of the larger structure, it is necessary to cut through the abrasive containing material which is not only difficult and time consuming, but can lead to inaccurate results and premature cutting tool wear.
U.S. Pat. No. 5,980,678 shows sintered abrasive materials having a pattern of first regions containing a plurality of abrasive particles and a second region adjacent to and surrounding the first region and fully integrated therewith containing no abrasive particles. The purpose is to form a patterned abrasive material having abrasive particles in some parts and no particles in others, but there is no suggestion to cut up the material to provide abrasive products of just the first regions or of the first regions with some of the second regions integrated therewith.
U.S. Pat. No. 5,620,489 also shows sintered abrasive material having a fist region containing a plurality of abrasive particles and a second region along one side thereof containing no particles fully integrated therewith. A purpose for the second region is to provide a xe2x80x9cfootxe2x80x9d to the first region containing no abrasive particles enabling the material to be more readily attached to a cutting tool. The reference discloses that such material can be cut up into pieces of the required shape and mounted on a suitable carrier. However, to provide such pieces it would be necessary to cut through not only the second region, but also the first region containing the abrasive particles.
In accordance with the invention, a new and improved method is provided for making an abrasive product comprising forming a structure of a sinterable retaining matrix having at least one first region containing a plurality of abrasive particles embedded therein and at least one second region containing substantially less or no abrasive particles adjacent said first region, at least one of said regions substantially surrounding the other of said regions, sintering said structure to form a unitary structure wherein said first and second regions are integrated along a border between said regions, and extracting at least said first region from said unitary structure to form an abrasive product.